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Saturday, September 25, 2010

Cloth Dyeing—Ancient and Modern

BY AWAKE! WRITER IN BRITAIN - April 2007

Have you ever noticed the effect that color has on our emotions? It is not surprising that throughout history humans have chosen to add color to fabrics, employing the process known as dyeing.

When we buy clothes and furnishings or the materials to make them, we do not want the colors to wash out or fade. To learn what processes are used in making fabrics colorfast and how traditional dyeing techniques developed, we visited the SDC Colour Museum at Bradford, in the north of England. There we saw examples of some of the unusual substances that have been used as dyes over the centuries.

Dyes Used in Early Centuries

Until the second half of the 19th century, the substances used for dyeing fabrics came entirely from natural sources, such as plants, insects, and shellfish. For example, the woad plant produced a blue dye (1), the weld plant a yellow dye (2), and the madder plant a red dye. A black dye came from the logwood tree, and a lichen named archil gave a violet dye. The murex shellfish produced a very costly purple dye, known as Tyrian, or imperial, purple (3). This dye colored the garments worn by Roman emperors.

Long before there were Roman emperors, the prominent and wealthy wore clothes dyed with natural substances. (Esther 8:15) Red dyes, for example, were produced from the female kermes insect (4). This was apparently the source of the coccus scarlet dye used for ancient Israel’s tabernacle furnishings, as well as for the garments of Israel’s high priest.—Exodus 28:5; 36:8.

The Process of Dyeing

Exhibits in the Colour Museum demonstrate that most dyeing processes are far more complex than simply dipping yarn or material into a dye solution. In many cases one stage of the dyeing process involves the use of a mordant, which is a substance that has an attraction for both the fiber and the dye. Through its use, dye bonds to the fiber and ceases to be water-soluble. Many chemicals are used as mordants, some of which are dangerous to handle.

Some dyeing processes create unpleasant smells. One of these is the lengthy and complex process that was used to produce Turkey red. This process was used on cotton and produced a bright-red color that was not affected by light, washing, or bleaching. At one time the process involved 38 different stages and took as long as four months to complete! Some of the most beautiful cloths on display at the museum are those that were dyed with Turkey red (5).

The Arrival of Synthetic Dyes

The first dye that was not derived from natural sources is attributed to William Henry Perkin in 1856. An exhibit explains Perkin’s discovery of mauve, or mauveine, an intense purple dye. By the end of the 19th century, many other synthetic dyes in brilliant colors had been developed. Today over 8,000 types of synthetic dyes are manufactured (6). The only natural products still in regular use are logwood and cochineal.

The Colour and Textiles Gallery of the Colour Museum explains the special processes needed today to dye synthetic materials, such as rayon. Viscose rayon, the most popular type of rayon in current use, was first produced commercially in 1905. As viscose rayon is chemically similar to cotton, most of the dyes available at that time were suitable for use. However, several new types of dyes had to be developed for more-modern synthetic materials such as acetate rayon, polyester, nylon, and acrylic fiber.

Challenge to Color Fastness

When we buy clothes or materials, we want them to be colorfast. Nevertheless, many fade in sunlight or with repeated washing, particularly if detergents are used. Sometimes fabrics may discolor from perspiration or change color when washed with other clothes. Fastness during the washing process depends on how strongly the dye molecules adhere to the fibers. Repeated washing and the effects of detergents designed to loosen stains separate the dye from the fibers, resulting in color loss. Dye manufacturers test their products to see if the effects of light, washing, detergents, and perspiration are within acceptable limits.

Our tour encouraged us to be more aware of what kinds of materials our clothes are made from. But more than that, we were enlightened regarding the ingenious processes that have been used to keep the colors in our clothing fixed despite frequent washing.